Adaptive operational full-duplex and half-duplex FDD modes in wireless networks

ABSTRACT

Methods and apparatus that enable a wireless network system to dynamically change between full-duplex FDD operation and half-duplex FDD operation in order to take advantage of operational aspects of both modes. In one embodiment, an alternative duplex mode of operation is disclosed (semi-static half duplex FDD operation) that enables coordination between the client device (e.g., UMTS UE) and the base station in order to centralize control of radio resource control (RRC) to the base station. The disclosed methods and apparatus may also advantageously incorporate hybrid ARQ (HARQ) or comparable timing requirements into their operation.

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BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates generally to the field of wirelesscommunication and data networks. More particularly, in one exemplaryaspect, the present invention is directed to methods and apparatus forflexible modes of operation in a transceiver.

2. Description of Related Technology

Universal Mobile Telecommunications System (UMTS) is an exemplaryimplementation of a “third-generation” or “3G” cellular telephonetechnology. The UMTS standard is specified by a collaborative bodyreferred to as the 3^(rd) Generation Partnership Project (3GPP). The3GPP has adopted UMTS as a 3G cellular radio system targeted for interalia European markets, in response to requirements set forth by theInternational Telecommunications Union (ITU). The ITU standardizes andregulates international radio and telecommunications. Enhancements toUMTS will support future evolution to fourth generation (4G) technology.

A current topic of interest is the further development of UMTS towards amobile radio communication system optimized for packet data transmissionthrough improved system capacity and spectral efficiency. In the contextof 3GPP, the activities in this regard are summarized under the generalterm “LTE” (for Long Term Evolution). The aim is, among others, toincrease the maximum net transmission rate significantly in future,namely to speeds on the order of 300 Mbps in the downlink transmissiondirection and 75 Mbps in the uplink transmission direction. To improvetransmission over the air interface to meet these increased transmissionrates, new techniques have been specified.

The current LTE specification describes several multiple access methods.For the downlink transmission direction, OFDMA (Orthogonal FrequencyDivision Multiple Access) in combination with TDMA (Time DivisionMultiple Access) will be used. Uplink data transmission is based onSC-FDMA (Single Carrier Frequency Division Multiple Access) incombination with TDMA. Further, LTE is expected to support full-duplexFDD, half-duplex FDD and TDD (time division duplexing).

FIG. 1A illustrates the aforementioned full-duplex FDD, half-duplex FDDand TDD according to the prior art. Full-duplex FDD uses two separatefrequency bands for uplink 122 and downlink 120 transmissions, and bothtransmissions can occur simultaneously. Unfortunately, full-duplexoperation has a fixed amount of bandwidth (typically symmetricallydivided between uplink 122 and downlink 120) allocated for data streams.Dynamically changing loads on the uplink 122 and downlink 120 datastreams waste spectral resources; even during periods of low data rate,the bandwidth must remain assigned.

Furthermore, full-duplex FDD requires a duplex filter in order toseparate the received waveform from the transmitted waveform. Thisduplex filter is “expensive” in terms of battery consumption, poweramplifier cost and radio frequency sensitivity, especially when viewedfrom the perspective of a UE (e.g., mobile device or handset)manufacturer.

Unlike FDD, TDD uses the same frequency band for transmission in bothuplink 122 and downlink 120. Within a given time frame, the direction oftransmission is switched alternatively between the downlink 120 anduplink 122. TDD systems have the benefit that receive and transmit arenot necessarily scheduled symmetrically, and can support uplink/downlinkdata variation more flexibly than Full-Duplex FDD. Furthermore, TDDoperation does not require a duplex filter because receive and transmitare on the same frequency band. The primary challenge for time-dividedsystems such as TDMA and TDD is the isolation of one time slot fromanother, necessary to minimize interference. Timing management ishandled by shifting transmission time to match the required time ofarrival. The 3GPP has standardized a variable timing advance (TA) tocontrol time synchronization between UE and base stations. Within a timeslot, the amount of time necessary to maintain isolation is wasted as itcannot be used for data transmission/reception, therefore lowerswitching rates are desirable.

Half duplex FDD uses two separate frequency bands for uplink 122 anddownlink 120 transmissions, similar to full-duplex FDD, but uplink anddownlink transmissions are non-overlapping in time. The main benefit ofhalf duplex FDD compared to full-duplex FDD is that the FDD duplexfilter can be replaced by a relatively simple switch fortransmit/receive separation. Unfortunately, half-duplex FDD operationmust be scheduled in the same manner as a time-divided (e.g., TDD)system. Furthermore, half-duplex FDD suffers from spectral inefficiencydue to incomplete frequency band usage (only one of the uplink 122 ordownlink 120 bands is active for a UE at any given point). However theadvantages of half-duplex FDD operation, as viewed from an operationalstandpoint of the base station, include allowing multiple UEs totime-share uplink and downlink resources. Accordingly, half-duplex FDDoperation can be implemented on FDD networks for managing large groupsof asymmetric data requirements, in a manner similar to TDD networks.

Half-duplex FDD operation in LTE systems is further described in TdocR1-080598, “Way forward for half duplex”, Ericsson et al., 14-18 Jan.2008, and Tdoc R1-080534, “Half Duplex FDD in LTE”, Ericsson, Nokia,Nokia Siemens Networks, 14-18 Jan. 2008, each of which is incorporatedherein by reference in its entirety. In current implementations of halfduplex operation in LTE networks, subframes are assigned to a UE foruplink or downlink transmission as a result of the scheduler operationin eNodeB. The eNodeB scheduler ensures that a UE is not transmittingand receiving in the same subframe. Accordingly, the UE is typicallyprepared to receive downlink (DL) transmissions in all subframes, anduplink (UL) transmissions are explicitly assigned through what is knownas a scheduling grant.

Due to the TDMA component of the LTE multiple access schemes in the ULand DL, so-called timing advance (TA) adjustments for the uplinktransmissions are utilized. These adjustments are implemented using asignal from a UE that arrives at the base transceiver station accordingto the determined frame/subframe timing, so that it does not interferewith the transmission of other UEs. A timing advance value correspondsto the length of time a UE has to advance its timing of UL transmission,and is sent by the eNodeB to the UE according to the perceivedpropagation delay of UL transmissions.

FIG. 1B is a detail of the prior art half duplex scheme shown in FIG.1A, with a chronology of the uplink and downlink transmissions labeled130, 132, and 134. As shown, the current proposal for implementation ofa DL-UL switch specifies that, for a UE receiving in sub-frame n 130 andtransmitting on sub-frame n+1 134, a reserved period 136 for UEswitching between receive and transmit shall be provided at the end ofthe downlink sub-frame 130 preceding the sub-frame 134 in which the UEis required to transmit. In a subframe 130 allocated for DL transmissiondirectly before an UL transmission is due, the time available for theactual data transmission is thus reduced by the period 136 for switchingfrom DL to UL and by the necessary TA. In conditions with rising TA, theTA will reduce the effective DL transmission time in this subframesignificantly. A drawback of this approach is that resources cannot beallocated to other UEs during the times of no DL transmission due to theTA and switching.

Similarly, for the UL-DL switch, a reserved period for UE switchingbetween transmit and receive is provided by timing advance means for theUE transmitting in subframe n 134 and receiving in subframe n+1 132. Asthe TA affects the transmission in subframe n 134 to stop before theboundary of the subframe 132, the switching period 138 can effectivelyuse the TA, and increasing TA will not negatively impact the ULtransmission efficiency.

The current working assumption is that a UE operating in an LTE radiocell will operate either in a full-duplex or a half-duplex FDD mode.Several solutions have been contemplated in the prior art to allow forboth full-duplex and half-duplex operation in wireless transmissionsystems. For example, U.S. Pat. No. 6,665,276 to Culbertson, et al.issued Dec. 16, 2003 and entitled “Full duplex transceiver” discloses anRF front end to an IF generator and post-processor whereby the IFgenerator output is variable. The transceiver up-conversion pathincludes an IF Filter, the output of which is input to a mixer with theoutput of a fixed Phase Locked Oscillator (PLO). The mixer output isinput to a band-pass filter and amplified. With a single antennaconfiguration, the amplifier output connects to either an internal orexternal diplexer that interfaces to the antenna. With a dual antennaconfiguration, the amplifier output interfaces directly to the antenna.Similarly, the down-conversion path includes an internal or externaldiplexer in the single antenna configuration, a band-pass filter, a RFamplifier, a mixer that receives the RF amplifier output and the fixedPLO as inputs, an IF Filter, IF amplifier, and an attenuator forinterfacing to the IF post-processor. A user-interface allows RF TX andRX frequency selection, data rate selection, and configurable optionsincluding internal or external diplexer, internal or external oscillatorreference, and TX amplifier keying to allow simplex, half duplex, orfull duplex communication.

U.S. Pat. No. 7,197,022 to Stanwood, et al. issued Mar. 27, 2007 andentitled “Framing for an adaptive modulation communication system”discloses a system and method for mapping a combined frequency divisionduplexing (FDD) Time Division Multiplexing (TDM)/Time Division MultipleAccess (TDMA) downlink subframe for use with half-duplex and full-duplexterminals in a communication system. Embodiments of the downlinksubframe vary Forward Error Correction (FEC) types for a givenmodulation scheme as well as support the implementation of a smartantennae at a base station in the communication system. Embodiments ofthe system are also used in a TDD communication system to support theimplementation of smart antennae. A scheduling algorithm allows TDM andTDMA portions of a downlink to efficiently co-exist in the same downlinksubframe and simultaneously support full and half-duplex terminals. Thealgorithm further allows the TDM of multiple terminals in a TDMA burstto minimize the number of map entries in a downlink map. The algorithmlimits the number of downlink map entries to not exceed 2n+1, where n isthe number of DL PHY modes (modulation/FEC combinations) employed by thecommunication system.

U.S. Pat. No. 7,339,926 to Stanwood, et al. issued Mar. 4, 2008 andentitled “System and method for wireless communication in a frequencydivision duplexing region” discloses a method and system for usinghalf-duplex base stations and half-duplex nodes in a Frequency DivisionDuplexing region to provide wireless connectivity between thehalf-duplex base stations and customers in multiple sectors of a cell.The method and system can use two physical channels to form two logicalchannels. Each logical channel shares both physical channels duringalternating frames of time. The half-duplex nodes can include amillimeter-wave band frequency synthesizer configured to transmit andreceive on different channels to and from the half-duplex base station.Re-use patterns of the physical channels are used for deployment ofhalf-duplex base stations and half-duplex nodes in the FDD region tominimize co-channel interference and interference due to uncorrelatedrain fade. Additional methods and systems utilize full-duplex basestations and smart antenna to communicate with the half-duplex nodes.

United States Patent Publication No. 20070054625 to Beale published Mar.8, 2007 and entitled “Compatible broadcast downlink and unicast uplinkinterference reduction for a wireless communication system” disclosesembodiments that reduce interference from a mobile station (UE) uplinktransmission to a received broadcast downlink transmission through anetwork-based scheduling of time-slotted downlink broadcasttransmissions, so that they do not occur concurrently with uplinktransmissions. UEs are designed and built to use: (i) downlink broadcasttransmissions that are time-slotted; (ii) UEs operate either inhalf-duplex mode for transmission and reception of unicast services, orin full duplex mode where additional bandpass or additional highpassfiltering can be applied to the DL unicast carrier; (iii) when unicastservices are active for a UE, the UE informs the network of thebroadcast services that are being decoded; and (iv) the networkschedules unicast transmissions, broadcast transmissions, or bothunicast and broadcast transmissions such that the uplink unicasttransmission to a UE is never time-coincident with the broadcasttransmissions to that UE.

Despite the foregoing, the prior art fails to provide an adequatesolution for dynamic switching capability between full-duplex andhalf-duplex operation in wireless transmission systems (such as cellularnetworks), such that the respective advantages of both modes canappropriately be utilized. Therefore, improved apparatus and methods forthe adaptive operation of full-duplex and half-duplex FDD modes in acellular system such as LTE is needed.

Such apparatus and methods would also ideally include a UE that maysupport both FDD modes, so that it can be adaptively switched betweenfull-duplex and half duplex FDD operation, rather than staticallyassigning modes of operation. In addition, it would advantageouslyfurther support additional modes of operation for half-duplex operation,and allow a UE to operate in a battery-efficient half duplex FDD mode aswell as improve cellular data throughput.

Further, such improved apparatus and methods would allow the network toopt to switch the UE transceiver mode to optimize data scheduling aswell as network resource utilization.

SUMMARY OF THE INVENTION

The present invention satisfies the aforementioned needs by providingimproved apparatus and methods for adaptive duplex operation.

In one aspect of the invention, a method of switching duplex operationin a wireless network is disclosed. In one embodiment, the wirelessnetwork comprises a plurality of networking devices, and the methodcomprises: operating the network in a first duplexing mode; detecting atrigger event within at least one of the plurality of networking devicesoperating in the first duplexing mode; determining a second duplexingmode of operation based at least in part on the detection of the triggerevent; distributing information about the change from the firstduplexing mode to the second duplexing mode to at least a portion of theplurality of networking devices; and operating the networking devices inthe second duplexing mode.

In one variant, the first duplexing mode comprises a default mode ofoperation for the network.

In another variant, the plurality of networking devices furthercomprises a serving station and a plurality of mobile stations. Theserving station may broadcasts the default mode of operation to theplurality of mobile stations.

In a further variant, the first duplexing mode comprises a half-duplexFDD mode of operation and the second duplexing mode comprises afull-duplex FDD mode of operation.

In still another variant, the trigger event is detected at a radioresource control (RRC) unit within the wireless network. The triggerevent may comprise for example reaching a threshold value in a timingadvance (TA) value. The threshold value may be for instance indicativeof a change in quality of service for the wireless network.

In a further variant, the trigger event comprises a higher quality ofservice request than the first duplexing mode can provide, and the firstduplexing mode comprises a half-duplex FDD mode of operation, and thesecond duplexing mode comprises a full-duplex FDD mode of operation.

In another variant, the trigger event is related to a battery status ofat least one of the plurality of mobile stations within the network.

Alternatively, the trigger event is selected from the group consistingof: timing advance variables in the network, data rates in the network;and battery status of at least a portion of the networking devices.

In still another variant, the first duplexing mode comprises ahalf-duplex FDD mode of operation and the second duplexing modecomprises a full-duplex FDD mode of operation; and the trigger eventcomprises a rising timing advance (TA) value.

Alternatively, the first duplexing mode comprises a full-duplex FDD modeof operation and the second duplexing mode comprises a half-duplex FDDmode of operation; and the trigger event comprises a falling timingadvance (TA) value.

In yet a further variant, the first duplexing mode comprises a dynamichalf-duplex FDD mode of operation and the second duplexing modecomprises a semi-static half-duplex FDD mode of operation; and thetrigger event comprises a rising timing advance (TA) value.

Alternatively, the first duplexing mode comprises a semi-statichalf-duplex FDD mode of operation, and the second duplexing modecomprises a dynamic half-duplex FDD mode of operation; and the triggerevent comprises a falling timing advance (TA) value.

In a second aspect of the invention, a client device capable ofoperating in a plurality of duplexing modes on a wireless network isdisclosed. In one embodiment, the client device comprises: a processingdevice coupled to a memory; a radio/modem subsystem coupled to theprocessing device; and a computer program resident within the memorythat when executed by the processing device, executes the methodcomprising: signaling a duplex component, directly or indirectly,resident within the client device to operate in a first duplexing modeof operation; and substantially in response to a detected trigger event,signaling the duplex component to operate in a second duplexing mode ofoperation.

In one variant, the first duplexing mode comprises a default mode ofoperation for the wireless network, and a serving station broadcasts tothe client device information invoking the default mode of operation,the signaling a duplex component being substantially in response to theserving station broadcast.

In another variant, the first duplexing mode comprises a half-duplex FDDmode of operation, and the second duplexing mode comprises a full-duplexFDD mode of operation, and the trigger event is detected at a radioresource control (RRC) unit within the wireless network and signaled tothe radio/modem subsystem of the client device. The trigger event maycomprise for example reaching a threshold value in a timing advance (TA)value, and/or may be indicative of a change in quality of service forthe wireless network. Alternatively, the trigger event comprises ahigher quality of service (QoS) level than the first duplexing mode canprovide.

In another variant, the client device further comprise a battery,wherein the trigger event is related to a charge or energy status of thebattery.

In a further variant, the first duplexing mode comprises a half-duplexFDD mode of operation and the second duplexing mode comprises afull-duplex FDD mode of operation; and the trigger event comprises arising timing advance (TA) value. Alternatively, the first duplexingmode comprises a full-duplex FDD mode of operation and the secondduplexing mode comprises a half-duplex FDD mode of operation; and thetrigger event comprises a falling timing advance (TA) value. As yetanother alternative, the second duplexing mode comprises a semi-statichalf-duplex mode of operation.

As yet another alternative, the first duplexing mode comprises a dynamichalf-duplex FDD mode of operation, and the second duplexing modecomprises a semi-static half-duplex FDD mode of operation; and thetrigger event comprises a rising timing advance (TA) value.

Alternatively, the first duplexing mode comprises a semi-statichalf-duplex FDD mode of operation, and the second duplexing modecomprises a dynamic half-duplex FDD mode of operation; and the triggerevent comprises a falling timing advance (TA) value.

In a third aspect of the invention, a method of operating a servingstation resident within a wireless network is disclosed. In oneembodiment, the serving station further comprising a logical connectionto a client device, and the method comprises: broadcasting a defaultduplexing mode of operation to the wireless network; detecting a triggerevent associated with the wireless network; determining that a differentduplexing mode of operation would benefit the wireless network; andsignaling the client device to operate in the different duplexing modeof operation.

In one variant, the default duplexing mode comprises a half-duplex FDDmode of operation, and the different duplexing mode comprises afull-duplex FDD mode of operation. The trigger event is detected ate.g., a radio resource control (RRC) unit within the serving station,and comprises reaching a threshold value in a timing advance (TA) value.The threshold value is indicative of a for instance change in quality ofservice for the wireless network.

In another variant, the trigger event comprises a higher quality ofservice level than the default duplexing mode can provide. The defaultduplexing mode comprises a half-duplex FDD mode of operation, and thedifferent duplexing mode comprises a full-duplex FDD mode of operation.

Alternatively, the default duplexing mode comprises a half-duplex FDDmode of operation, and the different duplexing mode comprises afull-duplex FDD mode of operation; and the trigger event comprises arising timing advance (TA) value.

As yet another alternative, the default duplexing mode comprises afull-duplex FDD mode of operation, and the different duplexing modecomprises a half-duplex FDD mode of operation; and the trigger eventcomprises a falling timing advance (TA) value.

Alternatively, the default duplexing mode comprises a dynamichalf-duplex FDD mode of operation, and the different duplexing modecomprises a semi-static half-duplex FDD mode of operation, and thetrigger event comprises a rising timing advance (TA) value.

As yet another alternative, the default duplexing mode comprises asemi-static half-duplex FDD mode of operation, and the differentduplexing mode comprises a dynamic half-duplex FDD mode of operation;and the trigger event comprises a falling timing advance (TA) value.

In an alternate variant, the network utilizes hybrid ARQ (HARQ)processing, and the serving station: identifies the use of the HARQprocessing; and implements only a subset of available duplex modes basedat least in part on the identifying. The serving station may alsocommunicate configuration information to the client device regarding thesubset.

In a fourth aspect of the invention, a wireless base station adapted formultiple duplex modes of operation is disclosed. In one embodiment, thebase station comprises a computerized device having a processor, memoryand at least one computer program adapted to implement dynamic duplexmode switching as part of at least one of uplink or downlinkcommunications with a UE in a UMTS network.

In a fifth aspect of the invention, a computer-readable apparatus isdisclosed. In one embodiment, the apparatus comprises a storage mediumadapted to store at least one computer program, the at least one programbeing adapted to cause a client device (e.g., UMTS UE) to operate in adefault duplexing mode of operation; detect a trigger event associatedwith the wireless network; determining that a different duplexing modeof operation would benefit the wireless network; and signaling theclient device to operate in the different duplexing mode of operation.In one variant, the apparatus comprises a hard disk drive (HDD) of acomputerized system. In another variant, the apparatus comprises a flashor other comparable memory.

In a sixth aspect of the invention, a digital communications systemadapted for dynamic duplex operation is disclosed. In one embodiment,the system comprises a UMTS wireless cellular system having a E-UTRANwith eNodeB, and at least one UE in wireless communication with theeNodeB. The system is optimized for at least one of spectral efficiencyand battery power conservation in the UE through selective applicationof the aforementioned dynamic duplex mode switching.

Other features and advantages of the present invention will immediatelybe recognized by persons of ordinary skill in the art with reference tothe attached drawings and detailed description of exemplary embodimentsas given below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a graphical representation of various prior art duplexmethods including full-duplex FDD, half-duplex FDD and TDD.

FIG. 1B is a graphical representation of DL-UL and UL-DL switching timesfor a half-duplex FDD operating mode in an exemplary prior art UMTSwireless system.

FIG. 2A is a functional block diagram of an exemplary embodiment of aprior art UMTS cellular system.

FIG. 2B is a functional block diagram of an exemplary prior art LTEnetwork architecture.

FIG. 3 is a logical flow diagram illustrating an exemplary communicationflow diagram for a simple prior art digital communications system.

FIG. 4 is a graphical representation of an exemplary frame structuretype for a prior art LTE FDD system.

FIG. 5A is a tabular representation illustrating an exemplary periodicUL-DL transmission pattern table of cyclically shifted transmissioncycles for a semi-static half-duplex FDD mode of operation in accordancewith the principles of the present invention.

FIG. 5B is a tabular representation illustrating an exemplary periodicUL-DL transmission pattern table of non-cyclically shifted transmissioncycles for a semi-static half-duplex FDD mode of operation in accordancewith invention.

FIG. 6 is a logical flow diagram of an exemplary embodiment of theswitching process for changing duplex modes in accordance with theinvention.

FIG. 7 is a graphical representation illustrating an exemplary controlmessaging flow between a UMTS UE and a base station in accordance withthe principles of the present invention.

FIG. 8 is a graphical representation illustrating an exemplary switchfrom a full-duplex FDD mode to a half-duplex FDD mode and back tofull-duplex FDD mode operation in accordance with the principles of thepresent invention.

FIG. 9 is a graphical representation illustrating an exemplary periodicUL-DL transmission pattern in accordance with the principles of thepresent invention.

FIG. 10 is a functional block diagram illustrating one embodiment of aUE apparatus adapted to implement the methods of the present invention.

FIG. 11 is a functional block diagram illustrating one embodiment of aserving base station apparatus adapted to implement the methods of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the terms “client device”, “end user device” and “UE”include, but are not limited to cellular telephones, smartphones (suchas for example an iPhone™), personal computers (PCs), such as forexample an iMac™, Mac Pro™, Mac Mini™ or MacBook™, and minicomputers,whether desktop, laptop, or otherwise, as well as mobile devices such ashandheld computers, PDAs, video cameras, set-top boxes, personal mediadevices (PMDs), such as for example an iPod™, or any combinations of theforegoing.

As used herein, the term “computer program” or “software” is meant toinclude any sequence or human or machine cognizable steps which performa function. Such program may be rendered in virtually any programminglanguage or environment including, for example, C/C++, Fortran, COBOL,PASCAL, assembly language, markup languages (e.g., HTML, SGML, XML,VoXML), and the like, as well as object-oriented environments such asthe Common Object Request Broker Architecture (CORBA), Java™ (includingJ2ME, Java Beans, etc.), Binary Runtime Environment (BREW), and thelike.

As used herein, the term “integrated circuit (IC)” refers to any type ofdevice having any level of integration (including without limitationULSI, VLSI, and LSI) and irrespective of process or base materials(including, without limitation Si, SiGe, CMOS and GaAs). ICs mayinclude, for example, memory devices (e.g., DRAM, SRAM, DDRAM,EEPROM/Flash, and ROM), digital processors, SoC devices, FPGAs, ASICs,ADCs, DACs, transceivers, memory controllers, and other devices, as wellas any combinations thereof.

As used herein, the term “memory” includes any type of integratedcircuit or other storage device adapted for storing digital dataincluding, without limitation, ROM. PROM, EEPROM, DRAM, SDRAM, DDR/2SDRAM, EDO/FPMS, RLDRAM, SRAM, “flash” memory (e.g., NAND/NOR), andPSRAM.

As used herein, the terms “microprocessor” and “digital processor” aremeant generally to include all types of digital processing devicesincluding, without limitation, digital signal processors (DSPs), reducedinstruction set computers (RISC), general-purpose (CISC) processors,microprocessors, gate arrays (e.g., FPGAs), PLDs, reconfigurable computefabrics (RCFs), array processors, secure microprocessors, andapplication-specific integrated circuits (ASICs). Such digitalprocessors may be contained on a single unitary IC die, or distributedacross multiple components.

As used herein, the terms “network” and “bearer network” refer generallyto any type of data, telecommunications or other network including,without limitation, data networks (including MANs, PANs, WANs, LANs,WLANs, micronets, piconets, internets, and intranets), hybrid fiber coax(HFC) networks, satellite networks, cellular networks, and telconetworks. Such networks or portions thereof may utilize any one or moredifferent topologies (e.g., ring, bus, star, loop, etc.), transmissionmedia (e.g., wired/RF cable, RF wireless, millimeter wave, optical,etc.) and/or communications or networking protocols (e.g., SONET,DOCSIS, IEEE Std. 802.3, 802.11, ATM, X.25, Frame Relay, 3GPP, 3GPP2,WAP, SIP, UDP, FTP, RTP/RTCP, H.323, etc.).

As used herein, the terms “network interface” or “interface” typicallyrefer to any signal, data, or software interface with a component,network or process including, without limitation, those of the FireWire(e.g., FW400, FW800, etc.), USB (e.g., USB2), Ethernet (e.g., 10/100,10/100/1000 (Gigabit Ethernet), 10-Gig-E, etc.), MoCA, Serial ATA (e.g.,SATA, e-SATA, SATAII), Ultra-ATA/DMA, Coaxsys (e.g., TVnet™), radiofrequency tuner (e.g., in-band or OOB, cable modem, etc.), WiFi(802.11a,b,g,n), WiMAX (802.16), PAN (802.15), IrDA or other wirelessfamilies.

As used herein, the term “wireless” means any wireless signal, data,communication, or other interface including without limitation Wi-Fi,Bluetooth, 3G (e.g., 3GPP, 3GPP2, and UMTS), HSDPA/HSUPA, TDMA, CDMA(e.g., IS-95A, WCDMA, etc.), FHSS, DSSS, GSM, PAN/802.15, WiMAX(802.16), 802.20, narrowband/FDMA, OFDM, PCS/DCS, analog cellular, CDPD,satellite systems, millimeter wave or microwave systems, acoustic, andinfrared (i.e., IrDA).

Overview

In one fundamental aspect, the present invention provides, inter alia,methods and apparatus that enable an FDD system to dynamically changebetween full-duplex operation and half-duplex operation in order to,inter alia, take advantage of operational aspects of both modes atappropriate times while minimizing any drawbacks associated therewith.These advantages include, for example, the flexible and dynamicswitching between options based on actual network conditions, reductionin transceiver power consumption on the UE, as well as improvements inspectral resource usage/efficiency.

In one embodiment, the UE operates in a first mode according to adefault network setting (or some other UE or network parameter). Thenetwork (and/or UE) then detects a trigger event, and determines asecondary mode of operation that would benefit the UE and/or network inone or more of the foregoing aspects. After deciding on a secondary modeof operation, information about the changes to be made are distributedonto the network so that other aspects of the network affected by thechange are kept informed. The UE devices on the network are allocatedspectral resources according to the second mode of operation, andsubsequently operate according to the changes made to the network.

In another aspect of the invention, an alternative duplex mode ofoperation (so-called “semi-static half-duplex” operation) is provided.Such semi-static half-duplex operation advantageously enablescoordination between the UE and the base station. In one embodiment, thesemi-static half-duplex operation centralizes control of radio resourcesto the base station, enabling the base station to schedule UE accessover guard slots, to further compact UE access to the network andenhance efficiency. It may also be used in a stand-alone fashion, or inconjunction with the aforementioned operational dynamic switching.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments of the present invention are now described indetail. While these embodiments are primarily discussed in the contextof a UMTS wireless network, and more specifically to fourth generationUMTS LTE networks, it will be recognized by those of ordinary skill thatthe present invention is not so limited. In fact, the various aspects ofthe invention are useful in any wireless network that can benefit fromthe dynamic switching of operational modes between transceivers as isdisclosed herein, such as for example those compliant with the 3GPP2initiative and standards, or IEEE 802.16 (WiMAX) systems. Moreover,while discussed primarily in the context of dynamic switching offull-duplex FDD to half-duplex FDD transceiver modes, it is recognizedthat other transceiver capabilities may be implemented without departingfrom the principles of the present invention described herein.

As is well known, a cellular radio system comprises a network of radiocells each served by a transmitting station, known as a cell site orbase station. The radio network provides wireless communications servicefor a plurality of transceivers (in most cases mobile). The network ofbase stations working in collaboration allows for wireless service whichis greater than the radio coverage provided by a single serving basestation. The individual base stations are connected by another network(in many cases a wired network), which includes additional controllersfor resource management and in some cases access to other networksystems (such as the Internet) or MANs.

In a UMTS system, a base station is commonly referred to as a “Node B”.The UMTS Terrestrial Radio Access Network (UTRAN) is the collective bodyof Node Bs along with the UMTS Radio Network Controllers (RNC). The userinterfaces to the UTRAN via User Equipment (UE), which in many typicalusage cases is a cellular phone or smartphone. FIG. 2A illustrates anexemplary UMTS cellular system 200 with focus on the radio network. TheUMTS system 200 comprises a plurality of base station towers 202 (NodeBs) that are set at various fixed geographic locations. Each of thesebase station towers 202 are characterized by their respective wirelesscoverage areas 204. The radio network controller 206 generally governsthe operation of the base station towers 202.

FIG. 2B illustrates the high-level network architecture for the fourthgeneration successor to the GSM/UMTS standard, also known as LTE. Asseen hi FIG. 2B, an LTE 250 system comprises the radio access networkE-UTRAN 252 (Evolved UMTS Terrestrial Radio Access Network) and the corenetwork EPC 254 (Evolved Packet Core). The E-UTRAN 252 comprises aplurality of base transceiver stations known as eNodeB (eNBs) 202. EacheNB 202 provides radio coverage 204 for one or more mobile radio cellswithin E-UTRAN 252. Control and user data are transmitted between arespective eNB 202 and a UE 256 in a mobile radio cell 204 over the airinterface on the basis of a multiple access method. For LTE, newmultiple access methods have been specified. For the downlinktransmission direction OFDMA (Orthogonal Frequency Division MultipleAccess) in combination with TDMA (Time Division Multiple Access) isused. OFDMA in combination with TDMA, subsequently also calledOFDMA/TDMA, is a multicarrier multiple access method in which asubscriber is provided with a defined number of subcarriers in thefrequency spectrum, and a defined transmission time for the purpose ofdata transmission. Uplink data transmission is based on SC-FDMA (SingleCarrier Frequency Division Multiple Access) in combination with TDMA.

The eNBs 202 are connected in the exemplary embodiment to the EPC 254(Evolved Packet Core) which comprises the MME (Mobility ManagementEntity) and the Serving Gateway (S-GW) 206. The MME is responsible forcontrolling the mobility of UEs 256 located in the coverage area ofE-UTRAN 204, while the S-GW is responsible for handling the transmissionof user data between UE 256 and network. Details of the radio accessnetwork and air interface for LTE systems are described in, inter alia,3GPP Technical Specification TS 36.300 entitled “E-UTRA and E-UTRAN;Overall description; Stage 2”, which is incorporated herein by referencein its entirety.

FIG. 3 illustrates an exemplary communication flow 300 for a digitalcommunication system such as the aforementioned UMTS system. Theillustrated communication flow begins at step 302, where an input signal(e.g., an analog voice signal or the like) is converted into a digitalrepresentation. This digital data stream is compressed to reduceredundant or unnecessary information in a process collectively referredto as source coding 304, as is well known in the digital processingarts. The compressed data stream is coded so as to be resistant to noisein a process collectively referred to as channel coding 306. This mayinclude for example forward error correction (FEC) coding such asconvolutional codes, Turbo codes or LDPCs. The channel coded output ispassed to a transmitter, and transmitted across a noisy medium 308(e.g., air interface). The receiver receives an input data stream fromthe transmission medium 310, with an expected amount of corruptionintroduced by the noise. The received data is passed through a datacorrection process 312 using the channel decoding methods describedabove to correct for transmission errors. The corrected data stream isdecompressed and re-assembled into a reproduction of the input signal314 using the source decoding methods described above. Lastly, theoutput signal 316 is passed to higher layer software for use ordistribution thereby.

In an UMTS-based system, the communication between Node B and UE operatein both uplink and downlink directions; i.e. both the Node B and the UE,transmit and receive. Uplink and downlink communications are commonlyimplemented using Frequency Division Duplex (FDD) and Time DivisionDuplex (TDD). FDD operation relies on separation between frequency bandsto prevent interference between channels, while TDD relies on separationbetween time slots to prevent interference between channels.

Frame Structure for FDD in LTE Networks—

In UMTS, data streams are subdivided in time to constant time intervals,or frames. Each frame is further subdivided into slots, and subframes.Not all subframes need to be in use (the network could beunderutilized), but a subframe is the smallest incremental amount ofdata to be used for transmission/reception with the transceivers. Once atransceiver has acquired the base station timing, subframes areallocated to each transceiver with a scheduling function.

An LTE network utilizes a standard frame structure type 1 400 (as shownin FIG. 4) which is used in both full-duplex and half-duplex FDD. Eachradio frame 406 is ten (10) ms in duration, and consists of twenty (20)slots 402 in 0.5 ms length intervals, numbered from 0 to 19. A subframe404 is defined as two consecutive slots 402. Ten (10) subframes 404 areavailable for downlink transmission, and ten (10) subframes 404 areavailable for uplink transmissions in each ten (10) ms interval. Uplinkand downlink transmissions are separated in the frequency domain.

Hybrid ARQ (HARQ)—

In LTE, a Hybrid Automatic Repeat Request mechanism (i.e., thecombination of channel coding and 8-channel Stop & Wait mechanism) isapplied as a method for backward error correction for both full duplexFDD and half duplex FDD operation. Each transmission of data (control oruser data in UL and DL) in a transport block in a subframe is positivelyor negatively acknowledged by the receiver by sending the informationindicating whether a transport block has been successfully received ornot. If successfully received, the sender is expected to send a new datablock in the next related subframe; if it is not successfully received,the sender is expected to re-transmit the data block in the next relatedsubframe.

For data blocks transmitted in the DL by the eNodeB, a fixedrelationship in time between data transmission and acknowledgements andbetween acknowledgements and re-transmissions exist. After a DLtransmission in subframe n, the UE is expected to acknowledge the DLdata reception in the subframe n+4. After an UL transmission in subframen, the eNodeB is expected to acknowledge the UL data reception insubframe n+4, and the UE is expected to re-transmit the data in case ofunsuccessful reception in subframe n+8. Due to the time dependencies ofHARQ processing, additional time requirements for half-duplex FDD arenecessary.

Any half-duplex scheme applied for LTE has to ensure that transmissionsin the UL and DL are carefully switched, so that for each transmissionthe related acknowledgements and re-transmissions can occur with thefixed time relation described. In other implementations of networksutilizing HARQ processing and half-duplex communication channels, thetime requirements may substantially differ. Furthermore, while HARQ isconsidered a time constraint that is essential for LTE operation, otheroperations may require separate time constraints (e.g., real-time orQoS-related data demands well known to the arts such as streamingvideo), or no significant time constraints at all (e.g. trickle type, orswarming type downloads).

Radio Resource Control (RRC)—

In the exemplary implementation, the RRC of the UMTS WCDMA protocolstack handles the control plane signaling between the UEs and UTRAN, and(among other functions) must perform connection establishment andrelease. For the efficient control of radio resources and communicationconnection between a UE and eNodeB, two connection states of interestare specified in the RRC protocol layer (i.e. RRC_IDLE andRRC_CONNECTED) of the UMTS LTE protocol stack. See for example, 3GPPTechnical Specification TS 36.331 entitled “E-UTRA Radio ResourceControl (RRC)”, incorporated herein by reference in its entirety. TheRRC connection is defined as a point-to-point bidirectional connectionbetween RRC peer entities in the UE and eNodeB, respectively. Inaddition, there typically is either zero or one RRC connection between aUE and eNodeB.

In the RRC_IDLE state discussed above, no RRC connection between the UEand UTRAN has been established. During the RRC_IDLE state, the UEperforms a variety of functions necessary for radio link management,such as cell selection/reselection, monitoring the paging channel, andacquiring system information broadcast in the radio cell. In this state,the UTRAN may maintain the UE position, known by the network at a“tracking area” level. A tracking area defines a group of cells wherethe UE in RRC_IDLE state registers, and where the UE is paged in case ofan incoming communication attempt. During RRC_IDLE operation, there isno transmission of user and control data in either uplink or downlink.

In the RRC_CONNECTED state, an RRC connection is established, and the UEand UTRAN must actively handle radio resource allocations. Networkcontrolled mobility is performed by explicit handover and cell changeorder. The UTRAN must maintain/update UE position, at the cell arealevel. The UE acquires system information which is broadcast in theradio cell. Transmission of user and control data in uplink and downlinkoccurs during the RRC_CONNECTED state. The RRC protocol layer isresponsible for broadcasting system level information, and formaintaining connection layer bi-directional control.

Semi-Static Half-Duplex FDD Mode—

In one embodiment of the invention, an alternate half-duplex FDD mode,referred to as semi-static half-duplex FDD mode, is provided. Theexemplary implementation of this semi-static half-duplex FDD mode ischaracterized by periodic UL-DL transmission patterns, although it willbe recognized that a periodic UL-DL transmissions may be practiced aswell. In one variant, a periodic UL-DL transmission pattern with aninfinite length is specified.

Each periodic transmission pattern consists of a number of UL and DLsubframes, as well as Guard Subframes (GS) where no transmissions takeplace. In one variant, allocating the guard subframes to a UE between DLand UL transmission subframes allows the UE to perform DL/UL switching.Advantageously, the radio resources in that Guard Subframe can beallocated to different users (e.g., UEs) in the network. Further, theperiodic transmission pattern can be adapted so that switching cannotoccur in a time interval that violates the UL and DL HARQ requirements.

In semi-static half-duplex FDD mode operation, certain constraints ontransmission patterns may be implemented to improve radio resourceusage. For example, the length of a given periodic transmission patternis N subframes. Configuration of transmission patterns (in terms ofnumber and length) is either system-wide (i.e. applicable to all LTEcells of an operator) or cell-specific (i.e. applicable only to a givenLTE cell). The transmission pattern configuration comprises a set ofbase transmission patterns and a set of cyclic shifted versions of thatbase transmission pattern. Additionally the transmission patternsallocated to some UEs in a cell can be applied in parallel with UEsoperating in dynamic half-duplex FDD mode as well as in full-duplex FDDmode as well.

FIG. 5A illustrates a first exemplary embodiment of a periodic UL-DLtransmission pattern in accordance with the principles of the presentinvention. In the embodiment of FIG. 5A, eight (8) configurations areshown for a length comprising eight (8) subframes. Each configurationconsists of three (3) DL subframes; three (3) UL subframes and a GuardSubframe (GS) between the UL and DL subframes. Each configurationcomprises a unique configuration where the UL and DL subframes areplaced sequentially within the overall frame structure. This minimizesthe amount of GS needed which is desirable as GS comprise a dead periodwhere no transmissions take place. Further, the periodic cycling betweenDL and UL every four (4) subframes ensures compliance with UL and DLHARQ requirements.

While FIG. 5A illustrates cyclical shifted semi-static scheduling, it isappreciated that the scheduling may comprise non-cyclical scheduling aswell. For example, FIG. 5B illustrates an exemplary embodiment of anon-cyclical shifted semi static scheduling table (note that theconfigurations of FIG. 5B have been lettered rather than numbered forsake of clarity). As can be seen in FIG. 5B, shifting does not occurbetween configurations. Furthermore, as demonstrated in FIG. 5B, whennon-sequential sets are defined, a much larger number of permutationsare possible, which advantageously satisfy varying data raterequirements. Cyclically shifted configurations are easier to calculate,and simpler to implement, however for certain data rates, and datarequirements, other formats may be used.

With reference to configurations A, B, C, and D (FIG. 5B);configurations A and B can be assigned to two users who require twicethe resources of the two users assigned configurations C and D. In theseconfigurations, HARQ timing is obeyed.

With reference to configurations E and F, these configurations wouldonly be possible for systems which can selectively enable and disableHARQ operation. Even though HARQ operation is disabled, at least oneuplink and one downlink frame must exist, so as to enable the UE tosignal to the eNB that the transmission is completed, or vice versa.Certain data configurations do not depend on perfect data fidelity, butare time dependent (such as MPEG encode/decode operations); for suchapplications, disabling HARQ operation may be reasonable. By removingthe HARQ requirement for configurations A, B, C, and D even moreflexible options for data service are possible.

With reference to configuration G, an asymmetric data load can besupported. This configuration could be helpful for inter alia amulti-streamed connection to a UE with one stream requiring dataintegrity (HARQ operation), and another stream which is allowably“lossy”. Such a case could occur during simultaneous file transfer, andreal-time MPEG streaming.

With reference to configuration H, neither uplink nor downlink activityis signaled. This configuration can only be signaled to the UE if the UEhas the ability to “wake up” at a later point in time. Such methods ofdiscontinuous transfer (DTX/DRX) are already well known to the arts, andmay be useful in the context of the communication system describedherein as well.

Alternative configurations provide enhanced operational flexibilitydepending on the resource requirements for the network, but come at ahigher software cost, and increase the complexity of both the UE and eNBcommunication.

For the semi-static half-duplex FDD mode of operation, eight (8)periodic transmission patterns are configured in the cell, as describedsubsequently herein with respect to FIG. 5A.

Methods—

Referring now to FIG. 6, a first exemplary process 600 for dynamicallyswitching between full-duplex FDD and half-duplex FDD operationaccording to the present invention is described. It will be appreciatedthat while the process of FIG. 6 is described in the context of an LTEUMTS system, it may be applied generally to other types of systems.

At step 602, the eNB and one or more UEs begin operating in a firstduplex mode (e.g., full-duplex, dynamic half-duplex or semi-statichalf-duplex). In one embodiment of the exemplary process 600, the UEsupports multiple FDD modes and selects one of the supported modes afterthe UE switches-on. The UE may then operate in a mode based on forexample the default settings specified by the network operator. In avariant of the first embodiment, the UE may decide to operate infull-duplex or half-duplex FDD mode based on implementation-specificdetails; e.g. depending on the battery status at the UE side, networkinformation received from the network, etc.

In one variant, the network signals its support of available modes tothe radio network (e.g., the supported FDD modes in the radio cell),which is then broadcast or otherwise sent to all UEs in the cell. Forexample, if the radio cell on which the UE is camped only supports oneof the FDD modes (e.g. full-duplex FDD), the UE changes its selected FDDmode after switch-on accordingly.

In another variant, if the radio cell on which the UE is camped doessupport multiple modes, explicit signaling is utilized between the UEand the eNB so that the UE knows which mode it should be operating in.Various other logical constructs or procedures for selecting anappropriate mode at startup will be recognized by those of ordinaryskill given the present disclosure, and accordingly are not describedfurther herein.

At step 604, a trigger event is detected either at the eNB or the UEs.In the exemplary embodiment, these trigger events comprise pre-definedevents, monitored by the eNB or UE, which are indicative of anopportunity to optimize or simply modify the current transceiveroperation. In one variant, the switch between full-duplex FDD mode andhalf-duplex FDD mode is triggered within the RRC although it isappreciated that the trigger could be implemented elsewhere within thenetwork. The trigger event comprises for example changes (i.e., risingor falling) in timing advance (TA) values. In another embodiment, thetrigger event comprises RRC mode changes in order to support a differingquality of service (QoS). For instance, the trigger event might occur ifthe RRC determines that the peak data rate required by the UE cannot beprovided in a half-duplex FDD mode; a trigger event (in the form of asignal message) will tell the RRC and/or the UE that a higher quality ofservice mode (such as the aforementioned full-duplex FDD mode) isneeded. For lossy applications, this threshold may be set below the peakdata rate required by the service; e.g., so that only the peaks of therate curve cannot be services, thereby resulting in a small butacceptable rate of loss, so that half-duplex operation can be maintainedunder certain circumstances where it is desirable for other reasons.

At step 606, an entity (either at the UE or at the network side)determines that the network operation can be optimized by changing theduplex mode. During this step, the entity may consider one or morefactors in its decision, such as for example timing advance (TA)variables, data rates, hardware capabilities, network operationalparameters, etc. In one variant of this embodiment, it is determinedthat the UE and eNB would benefit if switched from a half-duplex FDDmode to a full-duplex FDD mode if the TA value exceeds an upperthreshold, and thus DL transmission efficiency would decrease below anacceptable limit in the subframe in which the DL-UL switch occurs.Alternatively it may be determined that the UE and eNB would benefit ifswitched from a full-duplex FDD mode to a half-duplex FDD mode if the TAvalue falls below a lower threshold.

In yet another embodiment, semi-static half-duplex FDD mode isdetermined to be a mode of operation that best benefits the UE and eNB.This might be determined for example, if a timing advance (TA) valueexceeds an upper threshold, or conversely if the (TA) value falls belowa lower threshold, and then the UE is switched from semi-static todynamic half-duplex FDD mode.

At step 608, the network assigns one transmission pattern of theconfigured set of transmission patterns to each UE. Thereafter, the ULand DL transmissions will take place according to the definedtransmission pattern; i.e., eNodeB and UEs schedule the UL and DLtransmissions according to the defined transmission pattern. To ensurethat a plurality of UEs may be served efficiently, the configuredtransmission patterns are distributed among all UEs operating insemi-static half-duplex FDD mode (e.g., by usage of a uniformdistribution, for improving cell throughput—the Guard Subframes (GS) ineach transmission pattern for one UE are efficiently allocated to otherUEs to increase efficiency of the cell throughput).

At step 610, the network and serviced UE(s) switch over to the secondduplex mode synchronously. In one embodiment, the UE and base stationwill dynamically negotiate and modify connections using the RadioResource Control (RRC), and the UE transceiver mode is controlleddirectly by the base station. In one variant of this embodiment, the RRCprotocol layer at the base station maintains a connection between eachof the UEs, and controls the radio resources which are assigned to eachUE. The RRC is able to determine and schedule semi-static half-duplexoperation to optimize network utilization among the plurality of UEs.

At step 612, the eNB and one or more UEs begin operating in the secondduplex mode (e.g., full-duplex, dynamic half-duplex or semi-statichalf-duplex).

First Example

The following example further illustrates the switching from full-duplexFDD to a half-duplex FDD mode of operation according to the presentinvention in the context of one exemplary UMTS-based implementation.

An LTE radio cell supporting both full-duplex and (dynamic andsemi-static) half-duplex FDD modes comprises an RRC connection with asingle UE. The network signals its support of the FDD modes in the radiocell, via system information; which is broadcast to the UE in the cell.

For the semi-static half-duplex FDD mode of operation, eight (8)periodic transmission patterns are configured in the cell as illustratedin FIG. 5A. The length of each periodic transmission pattern is eight(8) subframes consisting of three (3) UL and three (3) DL subframeseach. The set of UL and DL subframes each is separated by one GuardSubframe (GS). Configuration 1 of FIG. 5A is the base transmissionpattern, whereas configurations 2 through 8 are cyclic shifted versionsof the base transmission pattern of configuration 1. These exemplarypatterns have a relationship in time between UL and DL transmissionswhich automatically meet HARQ timing requirements.

The exemplary UE supports both full-duplex FDD and half-duplex FDDmodes. The UE has selected full-duplex FDD mode after switch-on as aresult of default settings specified by the network operator (or the UEmanufacturer). The UE enters the RRC_CONNECTED state and performs avoice call. For the switch between full-duplex FDD and semi-statichalf-duplex FDD, and vice versa, the exemplary transmission framestructure and signaling flow is as illustrated in FIG. 7 and FIG. 8.

Referring now to step 702 of FIG. 7, while in the RRC_CONNECTED state,the UE is operated in full-duplex FDD mode. In response to timingadvance adjustments, the UE is switched from full-duplex FDD mode tosemi-static half-duplex FDD mode as the TA value falls below a specifiedthreshold value (which may be specified in a deterministic or derivativefashion as well). This switch is triggered by an explicit switch commandsent by eNodeB at step 704 (see also step 802 of FIG. 8).

At step 706, the network operates in a semi-static half-duplex FDD modeoperation, and the UE operates according to periodic transmissionpattern configuration 1 as further depicted in FIG. 9. As shown, theperiodic transmission pattern 900 is comprised of downlink transmissions902, uplink transmissions 904, and guard subframes 906. The uplinktransmission subframe N has a HARQ response at downlink transmissionsubframe N+4 (downlink subframe 0 carries the HARQ of preceding uplinksubframe No. 4, downlink subframe 1 carries the HARQ of preceding uplinksubframe No. 5, etc.). The guard subframes 906 are implemented at the UEonly, as the UE requires a small amount of time to switch from uplink todownlink and vice versa.

Due to further timing advance adjustments, the UE is switched back fromsemi-static half-duplex FDD to full-duplex FDD mode as the TA valueexceeds an upper threshold. This switch is triggered by an explicitswitch command by eNodeB at step 708 (See also step 804 of FIG. 8).After the switch, the UE is operated again in full-duplex FDD mode atstep 710.

Second Example

The following example illustrates an exemplary method for switchingbetween a dynamic half-duplex FDD mode of operation to a semi-statichalf-duplex FDD mode of operation implemented with multiple UEs.

For the semi-static half-duplex FDD mode operation eight (8) periodictransmission patterns are configured in the cell as illustrated in FIG.5A. The length of each periodic transmission pattern is eight (8)subframes consisting of three (3) UL and three (3) DL subframes each,the set of UL and DL subframes each is separated by one Guard Subframe(GS). Configuration 1 of FIG. 5A is the base transmission pattern,whereas configurations 2 to 8 are cyclic shifted versions of the basetransmission pattern. These exemplary patterns illustrated have arelationship in time between UL and DL transmissions which automaticallymeet HARQ timing requirements.

Four (4) UEs (UE1 through UE4) are in the RRC_CONNECTED state and areoperated in a dynamic half-duplex FDD mode. All four (4) UEs areperforming a voice call. It is assumed that due to timing advanceadjustments, the four (4) UEs are switched from dynamic to semi-statichalf-duplex FDD mode as the TA values for all UEs exceed an upperthreshold value. This switch is triggered by an explicit switch commandsent by eNodeB.

Within each dedicated switch command, each UE is assigned a periodictransmission pattern according to FIG. 5A. For improving cellthroughput; i.e. to efficiently use the introduced Guard Subframes (GS)in each transmission pattern where no transmissions take place, eNodeBassigns the transmission pattern: configuration 1 to UE1, configuration2 to UE2, configuration 6 to UE3 and configuration 8 to UE4.

After the switch, the UL and DL transmissions for each UE take placeaccording to the defined transmission pattern. In one illustrativeexample, during the post-transmission Guard Subframe of UE operating inconfiguration 1, UE operating in configuration 2 is able to transmit itsuplink. This overlapping of data transmission over guard subframes ispossible because the guard frames are observed by the UEs, but not bythe serving base station. In this manner, half-duplex FDD transmissionallows the UEs to efficiently use the spectral resources. The duplexeroperation is not necessary in half-duplex FDD allowing the UE toconserve resources such as power consumption.

Exemplary UE Apparatus—

Referring now to FIG. 10, exemplary client or UE apparatus 1000 usefulin implementing the methods of the present invention are illustrated.The apparatus disclosed comprises, inter alia, a UE such as a portablecomputer or mobile communications device capable of switching betweenfull-duplex and half-duplex modes. The base station functionality ispreferably performed in software, although hardware embodiments are alsoenvisioned; this apparatus is described subsequently herein with respectto FIG. 11.

The UE apparatus 1000 comprises an application processor subsystem 1028such as a digital signal processor, microprocessor, field-programmablegate array, or plurality of processing components mounted on one or moresubstrates 1002. The processing subsystem may also comprise an internalcache memory. The processing subsystem 1028 is connected to a memorysubsystem comprising memory which may for example, comprise SRAM 1018,flash 1020 and SDRAM 1022 components. The memory subsystem may implementone or a more of DMA type hardware, so as to facilitate data accesses asis well known in the art.

The radio/modem subsystem comprises a digital baseband 1016, analogbaseband 1006, RX frontend 1026 and TX frontend 1004. The apparatus 1000further comprises an antenna assembly 1012 and duplex component 1014;the duplexing component may comprise a simple switch 1014A for switchingbetween antenna operations. The switch 1014A may also comprise adiscrete component. While specific architecture is discussed, in someembodiments, some components may be obviated or may otherwise be mergedwith one another (such as RF RX, RF TX and ABB combined, as of the typeused for 3G digital RFs) as would be appreciated by one of ordinaryskill in the art given the present disclosure.

During a mode switch, an exemplary UE digital baseband modem 1016decodes a message from the UTRAN, instructing the UE to change modes viaa configuration assignment. The digital baseband modem 1016 fetches theconfiguration from the memory subsystem; in one embodiment thetransmission pattern configurations are pre-stored in flash 1020 fornon-volatile storage and loaded to SDRAM 1022 during modem operation.The transmission pattern configurations are used by the digital basebandmodem 1016 to appropriately schedule transmission and receptionoperation. In most instances, the digital baseband modem 1016 does nothave direct access to the duplexing/switching component 1014.

The Analog Baseband 1006 controls operation of the radio frontends andconverts a digital signal (input from the digital baseband modem 1016)to an analog representation for transmission. Therefore, the digitalbaseband modem 1016 loads the analog baseband 1006, with schedulingparameters for the upcoming frame. The duplexing component 1014 mayinclude a simple switch 1014A the control of duplex operation or switchoperation being controlled by the analog baseband 1006. The control ofTX and RX frontends are also controlled by the analog baseband 1006.

A combination duplexer and switch component provides a benefit in termsof both board space and interfaces; however, it may not always bepossible to combine these components, due to design issues, such asreverse compatibility or cost of redesign. The duplexer may be poweredoff when the UE is operating using the switching mechanism, therebysaving power consumption via obviating the costly duplexing operation.Powering off the duplexer is not strictly necessary for operation, andmay be ignored for systems which are not concerned with powermanagement, or are otherwise unable to toggle power to the duplexer.

A UE using a simple analog baseband 1006 which is unable to supporthalf-duplex operation may still be required to implement half-duplexoperation using general purpose I/Os (e.g., software activated switch)to control switching, so as to enable other UE on the network to operatein half-duplex. Due to the incompatibility of half-duplex operation withfull-duplex operation, any UE incapable of operating in half-duplexwould necessarily disable half-duplex operation for the entire communityof UEs. Therefore, in some embodiments, the control for switching may beimplemented in a separate interface from the duplexer on the analogbaseband 1006. In one embodiment, the simple switch 1014A may be aseparate assembly with a separate control mechanism controlled by theanalog baseband 1006. In other embodiments, the digital baseband 1016may need to directly control the duplexer/switch assembly; such a schememay not be preferable for the UE, but may be implemented for the benefitof other UE's within the network.

The illustrated power management subsystem (PMS) 1008 provides power tothe UE, and may comprise an integrated circuit and or a plurality ofdiscrete electrical components. In one exemplary portable UE apparatus,the power management subsystem 1008 advantageously interfaces with abattery 1010.

The user interface system 1030 comprises any number of well-known I/Oincluding, without limitation: a keypad, touch screen, LCD display,backlight, speaker, and microphone. However, it is recognized that incertain applications, one or more of these components may be obviated.For example, PCMCIA card type UE embodiments may lack a user interface(as they could piggyback onto the user interface of the device to whichthey are physically and/or electrically coupled).

The apparatus 1000 further comprises optional additional peripherals1024 including, without limitation, one or more GPS transceivers, ornetwork interfaces such as IrDA ports, Bluetooth transceivers, USB,Firewire, etc. It is however recognized that these components are notnecessarily required for operation of the UE in accordance with theprinciples of the present invention.

Exemplary Serving Base Station Apparatus—

Referring now to FIG. 11, exemplary serving base station apparatus 1100useful in implementing the methods of the present invention areillustrated. The base station apparatus 1100 comprises one or moresubstrate(s) 1108 that further include a plurality of integratedcircuits including a processing subsystem 1105 such as a digital signalprocessor (DSP), microprocessor, gate array, or plurality of processingcomponents as well as a power management subsystem 1106 that providespower to the base station 1100.

The embodiment of the apparatus 1100 shown in FIG. 11 at a high levelcomprises a broadcasting circuit configured to broadcast a defaultduplexing mode of operation to the wireless network; The broadcastingsubsystem comprises a digital baseband 1104, analog baseband 1103, andRF components for RX 1101 and TX 1102. While multiple subsystems areillustrated, it is appreciated that future developments may consolidatethe broadcasting subsystem, in whole or in part.

The processing subsystem 1105 may comprise a plurality of processors (ormulti-core processor(s)). Additionally, the procession subsystem likelyalso comprises a cache 1105A to facilitate processing operations. In thedisclosed invention, additional subsystems for triggering 1105B, modedetermination 1105C, and signaling 1105D are also required. Asillustrated in FIG. 11, these subsystems may be implemented in softwareor hardware which is coupled to the processing subsystem. Alternatively,in another variant, the subsystems may be directly coupled to thebroadcasting subsystem.

The disclosed embodiment of the present invention furthermore connectsthe detecting circuit 1105B, to the mode determining circuit 1105C, tothe signaling subsystem 1105D. The detecting circuit detects atriggering event associated with the wireless network. The determiningcircuit decides the duplexing mode of operation which would optimallybenefit the wireless network. The signaling circuit controls signalingto each of the client device(s) (e.g., UE) to operate in the differentduplexing mode of operation.

The processing subsystem 1105 is preferably connected to a memorysubsystem 1107. The memory subsystem comprises a direct memory access(DMA), operational random access memory (RAM) 1107B, and non-volatilememory 1107C.

It will be recognized that while certain aspects of the invention aredescribed in terms of a specific sequence of steps of a method, thesedescriptions are only illustrative of the broader methods of theinvention, and may be modified as required by the particularapplication. Certain steps may be rendered unnecessary or optional undercertain circumstances. Additionally, certain steps or functionality maybe added to the disclosed embodiments, or the order of performance oftwo or more steps permuted. All such variations are considered to beencompassed within the invention disclosed and claimed herein.

While the above detailed description has shown, described, and pointedout novel features of the invention as applied to various embodiments,it will be understood that various omissions, substitutions, and changesin the form and details of the device or process illustrated may be madeby those skilled in the art without departing from the invention. Theforegoing description is of the best mode presently contemplated ofcarrying out the invention. This description is in no way meant to belimiting, but rather should be taken as illustrative of the generalprinciples of the invention. The scope of the invention should bedetermined with reference to the claims.

What is claimed is:
 1. A method, comprising: at a user equipment (“UE”)connected to a wireless network: receiving a first indication that afirst duplexing mode is being used for the wireless network;transmitting a second indication to the wireless network that indicatesa condition present within the wireless network, wherein the secondindication communicates to the wireless network to determine whether asecond duplexing mode should be used for the UE, wherein the conditionis based on a characteristic of a wireless connection between the userequipment and the wireless network; receiving a third indication fromthe wireless network, the third indication including a location of atleast one guard subframe in a transmission pattern, wherein the guardsubframe comprises a period when no transmissions take place; andreceiving a fourth indication from the wireless network that the secondduplexing mode is being used for the wireless network, wherein thefourth indication further causes the UE to dynamically negotiate andmodify connections with the network using a Radio Resource Control(“RRC”).
 2. The method of claim 1, wherein the first duplexing modecomprises a half-duplex frequency division duplexing (“FDD”) mode ofoperation or a full-duplex FDD mode of operation.
 3. The method of claim2, wherein the second duplexing mode comprises a half-duplex FDD mode ofoperation or a full-duplex FDD mode of operation.
 4. The method of claim1, wherein the first duplexing mode comprises a dynamic half-duplex FDDmode of operation or a semi-static half-duplex FDD mode of operation;wherein the semi-static half-duplex FDD mode of operation centralizescontrol of radio resources to a base station, wherein the UE access isscheduled over guard slots.
 5. The method of claim 1, wherein the firstduplexing mode or the second duplexing mode comprises a time divisionduplexing (“TDD”) mode of operation.
 6. The method of claim 1, whereinthe condition comprises an energy status of a battery of the UE crossinga threshold.
 7. The method of claim 1, wherein the condition comprisesthe UE requiring a higher quality of service level.
 8. The method ofclaim 1, wherein the condition comprises a timing advance value crossinga threshold.
 9. A user equipment (“UE”), comprising: a processor,wherein the processor is configured to: receive a first indication thata first duplexing mode is being used for a wireless network; generate asecond indication that indicates a condition present within the wirelessnetwork, wherein the second indication communicates to the wirelessnetwork to determine whether a second duplexing mode should be used forthe UE, wherein the condition is based on a characteristic of a wirelessconnection between the user equipment and the wireless network; receivea third indication from the wireless network, the third indicationincluding a location of at least one guard subframe in a transmissionpattern, wherein the guard subframe comprises a period when notransmissions take place; and receive a fourth indication from thewireless network that the second duplexing mode is being used for thewireless network, wherein the fourth indication further causes the UE todynamically negotiate and modify connections with the network using aRadio Resource Control (“RRC”).
 10. The UE of claim 9, wherein the firstduplexing mode comprises a half-duplex frequency division duplexing(“FDD”) mode of operation or a full-duplex FDD mode of operation. 11.The UE of claim 10, wherein the second duplexing mode comprises ahalf-duplex FDD mode of operation or a full-duplex FDD mode ofoperation.
 12. The UE of claim 9, wherein the first duplexing modecomprises a dynamic half-duplex FDD mode of operation or a semi-statichalf-duplex FDD mode of operation; wherein the semi-static half-duplexFDD mode of operation centralizes control of radio resources to a basestation, wherein the UE access is scheduled over guard slots.
 13. The UEof claim 9, wherein the condition comprises at least one of an energystatus of a battery of the UE crossing a threshold, the UE requiring ahigher quality of service level, or a timing advance value crossing athreshold.
 14. A user equipment (“UE”), comprising: a receiver; atransmitter; and a processor coupled to the receiver and thetransmitter, wherein the processor is configured to: receive, from awireless network via the receiver, a first indication that a firstduplexing mode is being used for a wireless network; transmit, to thewireless network via the transmitter, a second indication that indicatesa condition present within the wireless network, wherein the secondindication communicates to the wireless network to determine whether asecond duplexing mode should be used for the UE, wherein the conditionis based on a characteristic of a wireless connection between the userequipment and the wireless network; receive, via the receiver, a thirdindication from the wireless network, the third indication including alocation of at least one guard subframe in a transmission pattern,wherein the guard subframe comprises a period when no transmissions takeplace; and receive, via the receiver, a fourth indication from thewireless network that the second duplexing mode is being used for thewireless network, wherein the fourth indication further causes the UE todynamically negotiate and modify connections with the network using aRadio Resource Control (“RRC”).
 15. The UE of claim 14, wherein thefirst duplexing mode comprises a half-duplex frequency divisionduplexing (“FDD”) mode of operation or a full-duplex FDD mode ofoperation.
 16. The UE of claim 15, wherein the second duplexing modecomprises a half-duplex FDD mode of operation or a full-duplex FDD modeof operation.
 17. The UE of claim 14, wherein the first duplexing modecomprises a dynamic half-duplex FDD mode of operation or a semi-statichalf-duplex FDD mode of operation; wherein the semi-static half-duplexFDD mode of operation centralizes control of radio resources to a basestation, wherein the UE access is scheduled over guard slots.
 18. The UEof claim 14, wherein the condition comprises the UE requiring a higherquality of service level.
 19. The method of claim 1, wherein the fourthindication causes the UE to switch from the first duplexing mode to thesecond duplexing mode, wherein the switch is controlled directly by abase station connected to the wireless network.